KR102139325B1 - Image pickup lens - Google Patents

Abstract

Embodiments include a first lens having a +power arrangement from an object side to an imaging side; -A second lens with a power arrangement; + A third lens with a power arrangement; + Fourth lens with power arrangement; And-a fifth lens having a power arrangement; in order, the first lens and the third lens provide an imaging lens having convex surfaces on both sides.

Description

Imaging lens {IMAGE PICKUP LENS}

The present invention relates to a five-sheet imaging lens.

Recently, conventional film cameras include camera modules for portable terminals that use small solid-state imaging devices such as CCDs and CMOSs, digital still cameras (DSCs), camcorders, and PC cameras (imaging devices attached to personal computers). It is being replaced with, and such an imaging device is mounted on various electronic products.

In such an environment, the imaging lens provided in the imaging device by various components provided in the electronic product needs to be developed with an imaging lens having miniaturization and high resolution in consideration of processing precision and cost.

The embodiment is intended to implement an imaging lens to compensate for changes over time due to temperature changes.

Embodiments include a first lens having a +power arrangement from an object side to an imaging side; -A second lens with a power arrangement; + A third lens with a power arrangement; + Fourth lens with power arrangement; And-a fifth lens having a power arrangement; in order, the first lens and the third lens provide an imaging lens having convex surfaces on both sides.

In addition, the second lens may have a meniscus shape.

In addition, the fourth lens may have a meniscus shape.

In addition, the fifth lens may have a meniscus shape.

Further, at least one of the first to fifth lenses may have an aspherical surface on one surface or both surfaces.

In addition, an aperture provided in front of the water side of the first lens or the second lens may be further included.

Further, the imaging lens may satisfy the first conditional expression 0.5 <Σd/f <1.5. Here, Σd is the thickness of the entire optical system (distance from the image-side surface of the first lens to the imaging surface), and f is the focal length of the entire optical system.

Further, the imaging lens may satisfy the second conditional expression 0.5 <f ₁ /f <1.5. Here, f ₁ represents the focal length of the first lens, and f represents the focal length of the entire optical system.

In addition, the imaging lens may satisfy the third conditional expression 1.6 <N ₂ <1.7. Here, N ₂ represents the refractive index of the second lens.

In addition, the imaging lens may satisfy the fourth conditional expression 2.0 <F _N <2.6. Here, F _N represents an F-number.

Further, the imaging lens may satisfy the fifth conditional expression 20 <V ₂ <30. Here, V ₂ represents the Abbe number of the second lens.

In addition, the imaging lens may satisfy the sixth conditional expression 50 <V ₁ , V ₃ , V ₄ , V ₅ , <60. Here, V ₁ is the Abbe number of the first lens, V ₃ is the Abbe number of the third lens, V ₄ is the Abbe number of the fourth lens, and V ₅ is the Abbe number of the fifth lens.

Further, the imaging lens may satisfy the seventh conditional expression 1 <R ₁₁ , R ₃₁ . Here, R ₁₁ represents the radius of the water side of the first lens, and R ₃₁ represents the radius of the water side of the third lens.

The embodiment is intended to implement an imaging lens for realizing high resolution and miniaturization.

1 is a configuration diagram of an imaging lens module according to a first embodiment of the present invention.
2 is a configuration diagram of an imaging lens module according to a second embodiment of the present invention.
3A is a graph showing a lateral aberration diagram according to a first embodiment of the present invention shown in FIG. 1;
3B is a graph showing astigmatism and distortion aberration diagram according to the first embodiment of the present invention shown in FIG. 1.
4A is a graph illustrating a lateral aberration diagram according to a second embodiment of the present invention shown in FIG. 2;
4B is a graph showing astigmatism and distortion aberration diagram according to the second embodiment of the present invention shown in FIG. 2.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Unless otherwise specified, all terms in this specification are the same as the general meaning of terms understood by those skilled in the art, and if the terms used in this specification conflict with the general meanings of the terms, the definitions used in the present specification are used.

However, the invention to be described below is only for describing the embodiments of the present invention and is not intended to limit the scope of the present invention, and the same reference numerals are used throughout the specification.

In addition, in describing the configuration of each lens in the present invention, "water side" means the surface of the lens facing the object side based on the optical axis, and "image side" refers to the optical axis. Refers to the surface of the lens facing the image side as a reference.

In addition, with respect to the features of each embodiment, two lens embodiments will be described below with reference to FIGS. 1 to 2, and thereafter, aberration diagrams according to each lens embodiment with reference to FIGS. 3A to 4B. Will be described in detail.

1 is a configuration diagram of an imaging lens module according to a first embodiment of the present invention.

Referring to FIG. 1, the imaging lens according to the first embodiment of the present invention includes a first lens 10, a second lens 20, a third lens 30, and a fourth lens 40 from an object side to an imaging side. , May include the fifth lens 50 in order, and may further include an aperture, a filter 60, and a light receiving element 70.

In FIG. 1,'S ₁ 'is the water side of the first lens 10,'S ₂ ' is the image side of the first lens 10,'S ₃ 'is the water side of the second lens 20, 'S _4' has a second and a side surface of the lens (20), 'S _5' are first and the image-side surface of the water side, 'S _6' of the third lens 30 has a third lens 30, 'it S ₇ 'is the fourth water side of the lens (40),' S ₈ 'is 4, and the image-side surface of the lens (40),' S ₉ 'are the water-side surface of the fifth lens (50),' S ₁₀ 'is a fifth It is the image side surface of the lens 50.

The member numbers (10 to 70) and'S _x'of these components can be equally applied to other embodiments shown in FIG. 2 of the present invention.

Referring to FIG. 1, the first lens 10 according to the first embodiment of the present invention has an object side convex shape, the second lens 20 has a water side convex shape, and the third lens 30 The upper surface side is convex, the fourth lens 40 has an upper side convex shape, and the fifth lens 50 has an upper side convex shape.

Specifically, the first lens 10 may have a convex shape on the image side, or may have both convex shapes.

The second lens 20 may have a concave shape with an image side surface or a meniscus shape convex toward the water side.

The third lens 30 may have a convex shape on the water side, and may have both convex shapes. Further, the third lens 30 may have an inflection point on at least one surface of the water side or the image side.

The fourth lens 40 may have a concave shape on the water side, or may have a meniscus shape convex toward the image side. In addition, the fourth lens 40 may have an inflection point on at least one surface of the water side or the image side.

The fifth lens 50 may have a concave shape on the water side, or may have a meniscus shape convex toward the image side. In addition, the fifth lens 50 may have at least one inflection point on at least one surface of the water side or the image side.

The lens shape represents a shape in the vicinity of the optical axis or optical axis.

In addition, the first lens 10 may have a + power arrangement, the second lens 20 may have a-power arrangement, and the fourth lens 40 may have a + power arrangement.

In addition, +, -, +, +,-in the order of the first lens 10 to the fifth lens 50, as described above, may have a power arrangement of PNPPN, which is the optical performance of the imaging lens, manufacturing cost And an optimal power arrangement set in consideration of downsizing of the imaging device.

In addition, the fifth lens 50 is preferably formed in a convex shape with an image side concave in the vicinity of the optical axis and convex toward the periphery. It is possible to make the angle of incidence of the light beam across the periphery close to perpendicular to the lens.

At least one of the first lens 10 to the fifth lens 50 is preferably one surface or both surfaces are aspherical. This is because when the aspherical surface of the first lens 10 to the fifth lens 50 is formed on at least one surface, it has an excellent effect in correcting various aberrations, particularly spherical aberration, coma aberration, and distortion aberration.

In particular, at least one of the first lens 10 to the fifth lens 30 may be provided as a plastic lens manufactured by injection molding. In addition, glass lens manufacturing may be included as necessary. Plastic lenses by injection molding are easy in asphericalization of lenses, and are advantageous for the production of small lenses.

The lens of the present invention includes a case where the surface is coated to prevent reflection or improve surface hardness.

On the other hand, the aperture is preferably located on the object side in the first lens 10 to the fifth lens 50 to secure telecentricity, and also, the first lens 10 or the second lens ( 20) may be located in front of the water side, but may be designed to be disposed between the second lens 20 and the third lens 30.

On the other hand, the filter 60 is an optical member, for example, a cover glass for protecting an imaging surface, an infrared filter (Infrared Ray Filter), or the like, and a flat-shaped optical member is disposed, and the light receiving element 70 may be an image sensor.

On the other hand, in the first embodiment, it is advantageous in terms of power balance of each lens and miniaturization and high performance of the imaging lens to satisfy any one of the following conditional expressions or each or a combination thereof.

<Conditional Expression 1>

0.5 <Σd/f <1.5

Here, Σd is the thickness of the entire optical system (distance from the image-side surface of the first lens to the imaging surface), and f is the focal length of the entire optical system.

<Conditional Expression 2>

0.5 <f ₁ /f <1.5

Here, f ₁ represents the focal length of the first lens, and f represents the focal length of the entire optical system.

<Conditional Expression 3>

1.6 <N ₂ <1.7

Here, N ₂ represents the refractive index of the second lens.

<Conditional Expression 4>

2.0 <F _N <2.6

Here, F _N represents an F-number.

<Conditional Expression 5>

20 <V ₂ <30

Here, V ₂ represents the Abbe number of the second lens.

<Conditional Expression 6>

50 <V ₁ <60

Here, V ₁ represents the Abbe number of the first lens.

<Conditional Expression 7>

50 <V ₃ <60

Here, V ₃ represents the Abbe number of the third lens.

<Conditional Expression 8>

50 <V ₄ <60

Here, V ₄ represents the Abbe number of the fourth lens.

<Conditional Expression 9>

50 <V ₅ <60

Here, V ₅ represents the Abbe number of the fifth lens.

<Conditional Expression 10>

1 <R ₁₁

Here, R ₁₁ represents the radius of curvature of the water side of the first lens.

<Conditional Expression 11>

1 <R ₃₁

Here, R ₃₁ represents the radius of curvature of the water side of the third lens.

The conditional expression for the radius of curvature of the lenses of the present invention makes aberration correction for each lens by satisfying some or all of them. That is, as the angle of incidence of the light flux in the imaging device is controlled at a constant angle, it is possible to reduce the amount of light imbalance in the image side.

Particularly, the conditional expression 2 as described above defines a condition range for the first lens 10 having relatively weak power, to preclude performance degradation mainly caused by manufacturing errors. Specifically, when the range is exceeded, the power of the first lens 10 becomes stronger, so that each aberration caused by the first lens 10 becomes large, and the second lenses 20 to fifth lenses ( 50) After this, the burden of correcting the aberration becomes large.

In addition, when the same condition as in the above conditional expression 10 is satisfied, it is advantageous to realize miniaturization of the imaging lens. Specifically, the full length of the imaging lens limited for miniaturization by greatly bringing the curvature radius of the water side of the first lens 10 It is possible to further increase the degree of freedom of the remaining lens curvature in length. In addition, by greatly increasing the radius of curvature of the water side of the fifth lens 50, it is easy to implement a shape that allows incident light to enter the surface of the fifth lens 50 in a tangential direction, thereby generating aberrations. Can be reduced.

The imaging lens according to the first embodiment of the present invention shown in FIG. 1 having such characteristics may have specific characteristics as shown in Tables 1 to 3 below.

Here, Table 1 is the aspherical coefficient of the first embodiment.

S _x k A B C D One -0.331838 -0.614030E-02 -0.106129E-01 -0.432889E-01 0.741766E-01 2 0.000000 0.660864E-01 -0.133867E+00 0.226224E+00 -0.824636E+00 3 0.000000 0.789616E-02 0.616917E-01 -0.711714E-01 -0.107518E+00 4 -11.997992 0.348185E-01 0.651101E-01 -0.587421E-02 -0.835424E-01 5 0.000000 -0.172722E+00 0.447193E-02 -0.152327E-01 0.595966E-01 6 0.000000 -0.660557E-01 -0.810071E-01 0.391722E-02 -0.115880E-01 7 0.000000 0.740647E-01 -0.684673E-01 0.920099E-02 0.000000 8 -1.000000 0.311120E+00 -0.331925E+00 0.315252E+00 -0.203483E+00 9 -3.199679 0.433781E-01 -0.398411E-01 0.732646E-02 0.292620E-02 10 286.973369 -0.141296E-01 0.495907E-01 -0.533414E-01 0.255942E-01

The aspherical surface referred to in the first embodiment is obtained from the well-known Equation 1, and the'E and the number following it' used for the conic constant k and the aspherical coefficients A, B, C, and D are powers of 10 Indicates. For example, E+01 represents 10 ¹ and E-02 represents 10 ^-2 .

Where z is the distance from the vertex of the lens to the optical axis

c: Basic curvature of the lens

Y: Distance in the direction perpendicular to the optical axis

K: Conic constant

A, B, C, D, E, F: Aspheric coefficient

Meanwhile, Table 2 below is lens data of each lens surface according to the first embodiment.

S _x Curvature radius (R) Thickness or distance (d) Refractive Index (N) material 1(stop) 1.8 0.62 1.53 Plastic 2 -5.8 0.05 3 35 0.28 1.64 Plastic 4 2.2 0.52 5 19.1 0.34 1.53 Plastic 6 -3.19 0.1 7 -1.47 0.76 1.53 Plastic 8 -0.78 0.21 9 -0.91 0.5 1.53 Plastic 10 -35.2 0.56 11 Infinity 0.21 1.52 IR-Filter 12 Infinity 1.76 Image 0.00 -0.02

On the other hand, Table 3 below is a value showing a specific specific value of the conditional expression of the first embodiment.

Embodiment 1 f 5.45 f ₁ 2.65 f ₂ -3.69 f ₃ 5.16 f ₄ 2.27 f ₅ -1.76 f ₁ /f 0.48 Σd 5.9 Σd/f 1.08 N ₁ , N ₃ , N ₄ , N ₅ 1.533 N ₂ 1.64 V ₁ , V ₃ , V ₄ , V ₅ 56.5 V ₂ 26 R ₃₁ 18 R ₃₂ -5.8 R ₅₁ 19.12 R ₅₂ -3.19

Here, f represents the focal length of the optical system, f _x is the focal length of the x-th lens, Σd is the overall thickness of the optical system, N _x is the refractive index of the x-th lens, V _x is the Abbe number of the x-th lens, and R _xy is x The radius of the water side (if y is 1) or the image side (if y is 2) of the second lens.

Meanwhile, FIGS. 3A and 3B are graphs showing an aberration diagram according to the first embodiment of the present invention, and FIG. 3A shows a lateral aberration according to the first embodiment of the present invention shown in FIG. 1. One graph, and FIG. 3B is a graph showing astigmatic field curves and distortion according to the first embodiment of the present invention shown in FIG. 1.

Referring to FIG. 3A, the lateral aberration defined by the difference between the position where the reference light beam enters the upper surface 70 and the position where the other light beam enters the upper surface 70 converges on the x-axis, thereby correcting the aberration. It is interpreted as good.

Referring to FIG. 3B, the Y-axis means the size of the image, the X-axis means the focal length (in mm) and the distortion (%), and as the curves approach the Y-axis, the aberration correction function is interpreted as good, According to this, in the imaging lens according to the first embodiment of the present invention, since the values of the images appear in the vicinity of the Y axis in almost all fields, the lateral aberration, astigmatism, and distortion aberration all show excellent values.

2 is a configuration diagram of an imaging lens module according to a second embodiment of the present invention.

Referring to FIG. 2, the first lens 10 according to the second embodiment of the present invention has a water-side convex shape, the second lens 20 has a water-side convex shape, and the third lens 30 Is a water-side convex shape, the fourth lens 40 has a water-side convex shape, and the fifth lens 50 has a water-side concave shape.

Specifically, the first lens 10 may have a convex shape on the image side, or may have both convex shapes.

The second lens 20 may have a concave shape with an image side surface or a meniscus shape convex toward the water side.

The third lens 30 may have a convex shape on the image side, and may have an inflection point on at least one surface of the water side or the image side.

The fourth lens 40 may have a concave shape on the water side, or may have a meniscus shape convex toward the image side. In addition, the fourth lens 40 may have an inflection point on at least one surface of the water side or the image side.

The fifth lens 50 may have a concave shape on the water side, or may have a meniscus shape convex toward the image side. In addition, the fifth lens 50 may have at least one inflection point on at least one surface of the water side or the image side.

The lens shape represents a shape in or near the optical axis.

In addition, the first lens 10 has a + power arrangement, the second lens 20 has a-power arrangement, the third lens 30 has a + power arrangement, and the fourth lens 40 ) Has a + power arrangement, and the fifth lens 50 has a-power arrangement.

On the other hand, +, -, +, +,-in the order of the first lens 10 to the fifth lens 50 as described above, that is, having a power arrangement of PNPPN is the optical performance, manufacturing cost and imaging device of the imaging lens It may be an optimal power arrangement set in consideration of miniaturization of.

In addition, the fifth lens 50 is preferably formed in a convex shape with an image side concave in the vicinity of the optical axis and convex toward the periphery. It is possible to make the angle of incidence of the light beam across the periphery close to perpendicular to the lens.

At least one of the first lens 10 to the fifth lens 50 is preferably one surface or both surfaces are aspherical. This is because when the aspherical surface of the first lens 10 to the fifth lens 50 is formed on at least one surface, it has an excellent effect in correcting various aberrations, particularly spherical aberration, coma aberration, and distortion aberration.

Meanwhile, in the imaging lens according to the second embodiment, any one or a part of the conditional expressions 1 to 10, or a combination thereof, or all of the conditional expressions 1 to 10 may be equally applied.

The imaging lens according to the second embodiment of the present invention shown in FIG. 2 having such characteristics may have specific characteristics as shown in Tables 4 to 6 below.

Here, Table 4 is the aspherical coefficient of the second embodiment.

S _x k A B C D One -0.313365 -0.547991E-02 -0.868549E-02 -0.481174E-01 0.718454E-01 2 0.000000 0.660864E-01 -0.133867E+00 0.226224E+00 -0.824636E+00 3 0.000000 0.789646E-02 0.616917E-01 -0.711714E-01 -0.107518E+00 4 -11.997992 0.348185E-01 0.651101E-01 -0.587421E-02 -0.835454E-01 5 0.000000 -0.112851E+00 -0.110291E-01 -0.487011E-01 0.362116E-01 6 0.000000 -0.539949E-01 -0.107750E+00 -0.285821E-02 -0.163524E-01 7 0.000000 0.740647E-01 -0.684673E-01 0.920099E-02 0.000000E+00 8 -1.000000 0.322042E+00 -0.329599E=00 0.315938E+00 -0.203155E+00 9 -3.435092 0.329487E-01 -0.498771E-01 0.511560E-02 0.445871E-02 10 486.932564 -0.390093E-01 0.597428E-01 -0.531814E-01 0.241803E-01

The aspherical surface referred to in the second embodiment is obtained from the well-known Equation 1 described in the first embodiment,'E used for the Conic constant k and the aspherical coefficients A, B, C, and D, followed by The number' represents the power of 10. For example, E+01 represents 10 ¹ and E-02 represents 10 ^-2 .

Meanwhile, Table 5 below is lens data of each lens surface according to the second embodiment.

S _x Curvature radius (R) Thickness or distance (d) Refractive Index (N) material One 1.82 0.59 1.53 Plastic 2 -7.63 0.1 stop Infinity 0.1 3 21.18 0.11 1.64 Plastic 4 2.15 0.53 5 4.21 0.71 1.53 Plastic 6 -4.23 0.36 7 -1.28 0.36 1.53 Plastic 8 -0.76 0.34 9 -0.83 0.5 1.53 Plastic 10 -55.16 0.56 11 Infinity 0.21 1.52 IR-Filter 12 Infinity 0.28 Image Infinity -0.11

On the other hand, Table 6 below is a value showing a specific specific value of the conditional expression of the second embodiment.

Example 2 f 4.35 f ₁ 2.81 f ₂ -3.74 f ₃ 4.07 f ₄ 2.50 f ₅ -1.59 f ₁ /f 0.64 Σd 5 Σd/f 1.15 N ₁ , N ₃ , N ₄ , N ₅ 1.533 N ₂ 1.64 V ₁ , V ₃ , V ₄ , V ₅ 56.5 V ₂ 26 R ₃₁ 1.82 R ₃₂ -7.63 R ₅₁ 4.21 R ₅₂ -4.23

Here, f represents the focal length of the optical system, f _x is the focal length of the x-th lens, Σd is the overall thickness of the optical system, N _x is the refractive index of the x-th lens, V _x is the Abbe number of the x-th lens, and R _xy is x The radius of the water side (if y is 1) or the image side (if y is 2) of the second lens.

Meanwhile, FIGS. 4A and 4B are graphs showing aberration diagrams according to the second embodiment of the present invention, and FIG. 4A shows lateral aberrations according to the second embodiment of the present invention shown in FIG. 1. FIG. 4B is a graph illustrating astigmatic field curves and distortion according to the second embodiment of the present invention shown in FIG. 2.

Referring to FIG. 4A, the lateral aberration defined by the difference between the position where the reference light beam enters the upper surface 70 and the position where the other light beam enters the upper surface 70 converges on the x-axis, thereby correcting the aberration. It is interpreted as good.

Referring to FIG. 4B, the Y-axis means the size of the image, the X-axis means the focal length (in mm) and the distortion (%), and as the curves approach the Y-axis, the aberration correction function is interpreted as good, According to this, in the imaging lens according to the second embodiment of the present invention, since the values of images in almost all fields appear adjacent to the Y-axis, lateral aberration, astigmatism, and distortion aberration all show excellent values.

According to the present invention, the lens material, lens shape and power distribution are optimized by the above technical features, and an imaging lens having excellent reliability in temperature change can be implemented.

As described above, those skilled in the art from the above description will be able to see that various changes and modifications can be made without departing from the technical spirit of the present invention. It should be determined by the scope and its equivalent.

10: first lens 20: second lens
30: third lens 40: fourth lens
50: fifth lens 60: filter
70: light receiving element

Claims (18)

In order from the object side to the top side,
A first lens having a positive power;
A second lens having negative power;
A third lens having positive power;
A fourth lens having positive power; And
It includes a fifth lens having a negative (-) power,
The distance between the second lens and the third lens is greater than the distance between the third lens and the fourth lens,
The imaging surface of the fifth lens is convex in the optical axis. According to claim 1,
The second lens is an imaging lens having a meniscus shape. According to claim 1,
The fourth lens is an imaging lens having a meniscus shape. According to claim 1,
The fifth lens is an imaging lens having a meniscus shape. According to claim 1,
At least one of the first to fifth lenses is an imaging lens having one surface or both surfaces aspherical. According to claim 1,
An imaging lens including an aperture provided in front of an object side surface of the first lens or the second lens. The method according to any one of claims 1 to 6,
The imaging lens satisfies the following conditional expression 1.
<Conditional Expression 1>
0.5 <Σd/f <1.5
Here, Σd denotes the distance from the image-side surface to the imaging surface of the first lens, and f denotes the focal length of the entire optical system. The method according to any one of claims 1 to 6,
The imaging lens satisfies the following conditional expression 2.
<Conditional Expression 2>
0.5 <f1/f <1.5
Here, f1 denotes a focal length of the first lens, and f denotes a focal length of the entire optical system. The method according to any one of claims 1 to 6,
The imaging lens satisfies the condition 3 below.
<Conditional Expression 3>
1.6 <N2 <1.7
Here, N2 represents the refractive index of the second lens. The method according to any one of claims 1 to 6,
The imaging lens satisfies the following conditional expression (4).
<Conditional Expression 4>
2.0 <FN <2.6
Here, FN represents an F-number. The method according to any one of claims 1 to 6,
The imaging lens satisfies the condition 5 below.
<Conditional Expression 5>
20 <V2 <30
Here, V2 represents the Abbe number of the second lens. The method according to any one of claims 1 to 6,
The imaging lens satisfies the following conditional expression 6.
<Conditional Expression 6>
50 <V1 <60
Here, V1 represents the Abbe number of the first lens. The method according to any one of claims 1 to 6,
The imaging lens satisfies the following conditional expression 7.
<Conditional Expression 7>
50 <V3 <60
Here, V3 represents the Abbe number of the third lens. The method according to any one of claims 1 to 6,
The imaging lens satisfies the following conditional expression 8.
<Conditional Expression 8>
50 <V4 <60
Here, V4 represents the Abbe number of the fourth lens. The method according to any one of claims 1 to 6,
The imaging lens satisfies the following conditional expression 9.
<Conditional Expression 9>
50 <V5 <60
Here, V5 represents the Abbe number of the fifth lens. The method according to any one of claims 1 to 6,
The imaging lens satisfies the following conditional expression 10.
<Conditional Expression 10>
1 <R11
Here, R11 represents the radius of curvature of the object-side surface of the first lens. The method according to any one of claims 1 to 6,
The imaging lens satisfies the following conditional expression 11.
<Conditional Expression 11>
1 <R31
Here, R31 represents the radius of curvature of the object side of the third lens. According to claim 1,
The imaging lens has a thickness greater than that of the fourth lens.

Images